body {
    margin: 0;
    font-size: 20px;
    padding: 0 100px;
}
h3 {
    margin: 0;
    padding: 0;
}
input[type='text'] , input[type='password']{
    height: 40px;
    width: 400px;
    padding-left: 20px;
    font-size: 24px;
}

input[type='checkbox']  {
    vertical-align: middle;
    width: 30px;
    height: 30px;
}

[class^="btn"] {
    padding: 5px 30px;
    height: 40px;
}

.header {
    width: 100%;
    height: 60px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: #f0f0f0;
    padding: 0 20px;
}
.btn-logout {
    border: 0;
    text-decoration: underline;
    padding: 5px 5px;
    cursor: pointer;
}
.header div span {
    color: red;
}